Corps asks to open spillway

With water levels in the Mississippi River expected to rise to 17 feet this month, the Army Corps of Engineers has officially made a request to the Mississippi River Commission that the Bonnet Carre Spillway be opened no earlier than May 9, according to Chris Brantley, project manager at the spillway.

Gov. Bobby Jindal indicated last week that the Bonnet Carre Spillway could be opened sometime between May 9 and May 13.
Water levels are currently approaching 14 feet at the Carrollton Gauge.

Spillway Road was closed by the parish on Tuesday evening due to flooding which posed safety concerns because of the threat of hydroplaning. It was reopened Wednesday morning.

“There was water across the roadway,” Brantley said. “To avoid accidents, (the parish) decided to shut down that highway.”

Brantley said the spillway is opened to protect areas down stream from flooding.

“We open (the spillway) to try to keep water going into New Orleans at no higher than 1.25 million cubic feet per second,” Brantley said. The current flow is at about 1.05 million cubic feet per second. “The flow still has to rise 200,000 cubic feet per second before the trigger point.”

Brantley said the Corps will continue to closely monitor the water while they wait to hear back from the Mississippi River Commission on opening the spillway. If the green light is given, he said it would take 36 hours, or three 12-hour work days, to completely open the spillway, but that usually they open a few bays at a time and continuously reevaluate the situation.

If the spillway is opened, it will be the ninth time since it was created in 1932. It was built after the 1927 flood and is designed to divert 250,000 cubic feet of water per second into Lake Pontchartrain.

The sudden rise in the river is mainly due to a huge rain system moving through the middle of the country, according to Mike Stack, chief of emergency operations at the Army Corps of Engineers New Orleans District.

“This is not a normal event. The rain event is larger than any average we would have,” Stack said. “The spillway on average would not get opened…but it looks like with the amount of water coming down, we’re going to quickly prepare (in case it needs to be opened).”

The spillway underwent an operational test on April 5 and Brantley said that everything went smoothly.

The last time the spillway was opened was in 2008 from April 11 through May 8 when the river crested at 16.69 feet. There are a total of 350 bays in the spillway, but only 160 were opened three years ago.

While opening the spillway would mean the total shutdown of Spillway Road, the news would not be all bad.

Brantley said that an infusion of river water would be good for the environment in the spillway.

“Additional sediments and nutrients from the Mississippi River would help feed the ecosystem in the spillway,” Brantley said. “It would be a good year for crawfish if the water comes in at the right time and ponds would be replenished.

“It would jumpstart the whole ecosystem.”

However, in 2008 the opening destroyed 28 areas of Spillway Road that took about six months to complete the almost $500,000 in repairs.

Brantley said that while no damage is anticipated if the spillway is opened this year, the area will be assessed and cleaned of sediments upon reclosing.

 

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